Bit by a tick on back of head a week ago, no rash, sore neck, swollen lymph nodes, flu like symptoms, soreness only getting worse. Should I go to er?

Primary Dr can check. On the west coast, the western black-legged tick can bite humans, and can cause lyme disease, after feeding for 24-48 hours. A lab can test such a tick for lyme disease bacteria. The doctor may treat with antibiotics if the lab finds lyme bacteria, if the bite site has a bull's-eye rash, or if there are other worries... Such as a lot of irritation and maybe a skin infection at the bite site.
No. You should see your health care provider on a non-urgent basis if there is any concern. This is not a problem for the emergency room.